Buying used heads?

[polkat]

I have a chance to get some 516 BB heads (yes, I know-hardly the best choice) but I can get then very cheaply. The seller states that they have been professionally ported. But after talking with him on the phone, he admitted that he had done the porting himself, following instructions from some un-named 'pro'.

Well, a beginner at porting can sometimes ruin a set of heads just as easily as helping them. I'll be looking at them tomorrow. What should I look for to tell if they are usable? Too much off the short side? Too much out of the bowls? Runners too big or possibly punched through? Any advice?

 

[ykf7b0]

Other than making sure he hasn't cut into the water jackets, you won't be able to tell a great deal about them unless he can produce some flowchart numbers. The one good thing about these heads is they are closed chamber. You can pick up a set of mid-70's heads -open chamber (ex. 452's)- for a low price and they will have the hardend exhaust valve seats already installed.

 

[Meep-Meep]

The 516's have a flat port floor so not too much can be screwed up unless they hit water. Hopefully it's just a bowl clean up and gasket match.

Check all threads

Measure with calipers the thickness of the head from the spot face on the lower row of head bolts to the gasket surface. Should be 1" nominal.

Guides knurled or replaced and if replaced what kind?

Valve to guide fit

Valve stems at equal heights?

Seats installed?